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L L Vertuno

Publications and source records attributed to L L Vertuno.

27 records · Page 2Linked to original sources
PubMed1979

Vascular access: long-term results, new techniques.

Effective approaches to unique problems of vascular access in renal failure have evolved from a five-year experience with 840 angioaccess procedures. Standard techniques plus innovations have required only 0.62 operations per year per patient with an average access life of 1.6 years. Classical forearm external arteriovenous (AV) cannulas and internal AV fistulas provided vascular access in 392 patients, while 61 required more complex procedures due to failure of primary cannulas and fistulas, inherently small forearm vessels, and iatrogenic vessel loss. Secondary techniques include reverse fistula, vascular graft AV fistulas using expanded polytetrafluoroethylene (E-PTFE), and arterioarterial (AA) jump graft. Presently, the new renal failure patient receives a forearm radiocephalic AV fistula; the cannula is restricted to emergency or short-term hemodialysis and may later be converted to a subcutaneous fistula. The reverse fistula is attempted before using E-PTFE grafts. Upper extremity AV and AA loops can then be constructed de novo or from the reverse fistula.

Arm↗
PubMed1973

Effects of glutamine deamination on glutamine deamidation in rat kidney slices.

Glutamate is known to inhibit the activity of isolated glutaminase I; however, its actual physiologic importance in regulating renal ammoniagenesis has not been established. To determine the regulatory role of glutamate on the metabolism of glutamine by rat kidney slices, we followed the effects on glutamine (2 mM) deamidation of increased removal of glutamate via augmented deamination. Three agents (malonate, 2,4-dinitrophenol, and methylene blue) were known to and shown here to hasten exogenous glutamate deamination. In slices from 10 control rats, 21.5+/-1.7 (SEM) mumol/g of ammonia were formed from amide nitrogen and 9.3+/-0.5 (SEM) mumol/g from the amino nitrogen of glutamine in vitro. Over 90% of the glutamine deamidated formed glutamate at one point in its catabolism. After addition of malonate (10 mM), 2,4-dinitrophenol (0.1 mM), or methylene blue (0.5 mM), the production of ammonia from the amino group rose to 29.3+/-6.0 (SEM) mumol/g, 20.0+/-1.8 (SEM) mumol/g, and 15.5+/-4.2 (SEM) mumol/g, respectively; ammonia production from the amide nitrogen rose also, 45.1+/-7.3 (SEM) mumol/g, 39.7+/-2.6 (SEM) mumol/g, and 41.9+/-3.7 (SEM) mumol/g. In the case of the former two, a minimum of 99% and 75% of the glutamine catabolized formed glutamate. Despite increased glutamine catabolism, there was no build up of glutamate in the media. A correlation between the formation of ammonia from the amino and amide nitrogen was apparent. Since none of the three agents selected affected phosphate activated glutaminase I activity directly or appeared to affect glutamine transport, we interpret the increase in deamidation as an expression of deinhibition of glutaminase I activity secondary to lowered glutamate concentrations at the deamidating sites through more rapid removal of glutamate via hastened deamination. Interestingly, slices removed from acidotic rats produced more ammonia from both the amino 29.1+/-3.8 (SEM) and amide nitrogens 45.9+/-4.3 (SEM) of glutamine, without a buildup of glutamate in the medium. At least 90% of the glutamine deamidated formed glutamate. A common mechanism is proposed to explain these results and the previous ones.

Acidosis↗